On Mon, Feb 10, 2020 at 8:53 PM H.J. Lu <hjl.to...@gmail.com> wrote: > > On Mon, Feb 10, 2020 at 11:40 AM Uros Bizjak <ubiz...@gmail.com> wrote: > > > > On Mon, Feb 10, 2020 at 8:22 PM H.J. Lu <hjl.to...@gmail.com> wrote: > > > > > > Since nested function isn't only called directly, there is ENDBR32 at > > > function entry and we need to skip it for direct jump in trampoline. > > > > Hm, I'm afraid I don't understand this comment. Can you perhaps rephrase it? > > > > ix86_trampoline_init has > > /* Compute offset from the end of the jmp to the target function. > In the case in which the trampoline stores the static chain on > the stack, we need to skip the first insn which pushes the > (call-saved) register static chain; this push is 1 byte. */ > offset += 5; > disp = expand_binop (SImode, sub_optab, fnaddr, > plus_constant (Pmode, XEXP (m_tramp, 0), > offset - (MEM_P (chain) ? 1 : 0)), > NULL_RTX, 1, OPTAB_DIRECT); > emit_move_insn (mem, disp); > > Without CET, we got > > 0000011 <bar.1878>: > 11: 56 push %esi > 12: 55 push %ebp <<<<<< trampoline jumps here. > 13: 89 e5 mov %esp,%ebp > 15: 83 ec 08 sub $0x8,%esp > > With CET, if bar isn't only called directly, we got > > 00000015 <bar.1878>: > 15: f3 0f 1e fb endbr32 > 19: 56 push %esi > 1a: 55 push %ebp <<<<<<<< trampoline jumps here. > 1b: 89 e5 mov %esp,%ebp > 1d: 83 ec 08 sub $0x8,%esp > > We need to add 4 bytes for trampoline to skip endbr32. > > Here is the updated patch to check if nested function isn't only > called directly,
Please figure out the final patch. I don't want to waste my time reviewing different version every half hour. Ping me in a couple of days. Uros. > > > -- > H.J.
